There are several known means of measuring the level of particulate material entrained in a gas flow. These can be split into a number of categories including those based on electrostatic or triboelectric phenomena on the one hand, and those based on optical phenomena on the other.
As will be appreciated by a person skilled in the art, known particulate emission monitors have various drawbacks, such as, limited sensitivity to light particles, a tendency to have display velocity dependence in their measurements, non linearity between particle concentration and detector signal and limited diagnostic capabilities, to name but a few.
The applicant does not concede that the prior art described herein is part of the common general knowledge at the priority date of the application.